It is well known in the transportation industries to attempt to achieve some degree of desired temperature control, using, for example, gel packs, "dry ice" (frozen carbon dioxide) and the like. However, these products have very limited capabilities in the period of time they can affect the desired temperature and/or pose significant safety hazards.
The present invention solves or at least substantially diminishes these prior art problems with sheets of packet materials which include porous cells containing a superabsorbent polymer. These packet sheets are initially submerged in water, hydrating them, and the hydrated sheets are then frozen (for cooling effects) or heated (for heating effects) and placed in juxtaposition to the goods to be cooled/heated. As the sheet(s) begin, for example, to warm up or thaw, the absorbed water goes directly from the frozen state into a gaseous state, avoiding wetness problems. The cells are formed in packets, producing longitudinally and laterally extended separation lines, which allow the completed packet sheets to be folded about either or both axes and thus contoured around the goods being cooled (or heated).
The background of the present invention goes back to the beginning of the breakthrough technology initially suggested in PCT/US92/06486 (published as WO 93/02861 on Feb. 18, 1993) and invented by George Barrett (now deceased), a predecessor to the work that led up to the present invention. In this PCT application there was disclosed an experimental device formed from composite sheets, namely two, layers of laminated textile material, one of which was semi-permeable to moisture, fused or otherwise sealed together, containing between them discrete quantities of a superabsorbent material in cells arrayed in a regular pattern, which superabsorbent readily absorbed water and could then be frozen to provide a substitute for ice and dry ice. The composite sheets were sealed or bonded together using rollers and applying heat and pressure. The fabric used allowed forming such bonds by thermoplastic fusing and the specification, in an off-hand manner, included the statement "or may involve a suitable adhesive" (page 5, line 1) without any further reference or explanation but instead speaks solely of forming the bond between the sheets using only the sheet materials themselves and heat and pressure to form the bond. As noted on page 7, line 10+, "The fabrics are selected to allow formation of a secure bond there-between using heat and pressure produced in the subject machine." and at page 9, line 16 "The bond is formed under the influence of the heat and pressure thus applied to the bonding area [the area surrounding the cells]." There thus appears to be a teaching away from the use of an adhesive, and there is absolutely no suggestion of putting an adhesive in the areas where the cells are formed, as in the present invention.
The disclosure of this publication is likewise incorporated herein by reference, except for its teaching away from there being an adhesive layer added to one of the layers of sheet material.
In or about 1994 there was a commercialization of such packet sheets using a superabsorbent, single cross-linked polymer (herein after referred to as the "1994 technology" or "1994 product"), described more fully below.
In subsequent U.S. Pat. No. 5,628,845 entitled "Process for Forming Hydratable, Flexible Refrigerant Media" issued May 13, 1997 (filed Sep. 28, 1995) by Murray (a co-inventor hereof) et al, the disclosure of which is incorporated herein by reference, describes the materials to be used in connection with the process to make the flexible refrigerant media as follows:
"a length of impermeable thermally formable media such as a plastic film, for example a 1.22 mil one side sealable biaxially oriented polypropylene film or a 1.75 mil coextruded multiply film including layers of high density polyethylene, a tie layer and a sealant layer. The foregoing examples are not intended to be limiting in as much as the apparatus and process may be used with a number of medias which lend themselves to thermal and pressure bonding." (Col. 2, lines 40-48.); PA1 "a length of a semi-permeable media such as a non-woven fabric. As used herein and as generally understood non-woven fabrics are made directly from fiber rather than yam (sic) by bonding or interlocking of fibers or both, accomplished by mechanical, chemical, or solvent means and combinations thereof. The non-woven fabric and the plastic film are both preferentially a standard width, such as sixty inches" (Col. 2, lines 49-56.); and PA1 a "quantity of superabsorbent polymer media appropriately selected from the known superabsorbents such as crosslinked acrylics; starch-graft polymers; cross-linked glycote and cellulose esters; and generally refers to water swellable polymers capable of at least a ten fold absorption of aqueous fluids forming a gel which holds fluids by a physicochemical reaction that is resistant to fluid loss under pressure. In the preferred embodiment, the polymer is powder-like or particulate in nature . . . " (Col. 3, lines 24-34.)
The present invention is directed to a vastly improved and innovative porous, laminated, superabsorbent, hydratable, temperature control pack system, which is able to maintain, for example, its cooling temperature characteristics more than eight (8) times longer than the 1994 technology's hydratable temperature control packet, a factor of more than eight-to-one (&gt;8:1), indicating a difference in kind rather than merely of degree. Additionally, the preferred embodiment of the invention is much stronger and more reliable than the predecessor product.
For further background informational purposes, not prior art purposes, it is noted that, in the above-referenced patent application Ser. No. 08/893,405, the materials disclosed for the plastic film layer is "plastic Polypropylene," for the porous web material "a non-woven fabric such as 2 oz. Polypropylene" and for the absorbent particulate matter "a super absorbent polymer such as sodium polyacrylate, crosslinked."
A listing of prior patents and other publications, which may be relevant to the invention, is presented below:
U.S. Pat. No. Patentee(s) Issue Date 4,223,043 Johnson 80/09/16 4,324,111 Edwards 82/04/13 5,147,343 Kellenberger 92/09/15 5,150,707 Anderson 92/09/29 5,313,809 Issacson et al 94/05/24 5,628,845 Murray et al 97/05/13 5,628,845 Murray et al 97/05/13 5,709,089 Dawson et al 98/01/20
The '089 patent to Dawson and Browne (the latter being a co-inventor of the Murray '845 patent) is not necessarily "prior art" to the present invention, as part of the present invention was made prior to its filing date of Mar. 4, 1996 and the invention itself was made prior to its issue date. In the '089 patent the specification is directed to a bag in whose interior there is a pouch containing a superabsorbent polymer, with the pouch wall having a water permeable portion of a non-woven fabric material. The '809 patent suggests that the water permeable layer could be attached to the water impermeable layer by heat sealing, gluing or the like. As a superabsorbent the patent suggests the use of "Sunwet IM-5700-D" of Sanyo Chemical K.K., a superabsorbent which is not, it is believed, multiply-linked polymer. There is likewise no suggestion of using a supplemental adhesive layer between the sheet materials or, more particularly, where the polymer powder is to be located or placed.
The '089 patent lists the following patents as pertinent art:
 U.S. Pat. No. Patentee(s) Issue Date 3,066,847 Fortune 62/12 3,559,416 Cornwall 71/02 4,181,285 Vangedal-Nielsen 80/01 4,404,820 Romaine 83/09 4,596,250 Beisang et al 86/06 4,780,117 Lahey et al 88/10 4,856,651 Francis, Jr. 89/08 5,031,418 Hirayama et al 91/07 5,035,241 Walasek et al 91/07 5,054,290 Hogan 91/10 5,150,707 Anderson 92/09 5,263,479 Tesch 93/11 5,271,244 Staggs 93/12 5,393,462 Avery 95/02 5,417,276 Dobry 95/05 5,447,532 Furuya 95/09
while noting that the '418 patent discloses a cooling package utilizing a superabsorbent polymer as one element thereof. The '089 patent specification also references a publication by "Thermonics Incorporated"; 4513 Old Shell Road, Mobile, Ala. 36608, a company with which two of the co-inventors hereof had a relationship.
Also note the above discussed PCT/US92/06486 application by George Barrett (published Feb. 18, 1993, WO 93/02861). It also is noted that the Kellenberger '343 patent includes information on superabsorbent materials and the meaning of superabsorbency.
For general background, informational, not prior art, purposes, reference is also had to the article entitled "Pharmaceutical shipments chill out from within" from the January 1998 edition of Packaging World (a Summit publication, One IBM Plaza, Suite 3131, 330 N. Wabash Ave., Chicago, Ill. 60611; note p. 38), which article discusses some of the beneficial effects of the inventors' test prototypes.